import Foundation
@testable import Closer

/// Deterministic test fake for `FirestoreInvitesProtocol`.
///
/// Simulates the server-side invite create/accept flow in memory:
/// - `createInvite` stores the E2EE fields keyed by the invite code.
/// - `acceptInvite` returns those fields plus deterministic `coupleId` and
///   `inviterUserId`, mirroring `acceptInviteCallable`.
///
/// No Firebase network is exercised.
public final class MockFirestoreInvites: @unchecked Sendable, FirestoreInvitesProtocol {
    private var invites: [String: InvitePayload] = [:]
    private let lock = NSLock()

    public var lastAcceptedCode: String?
    public var nextCoupleId = "couple-mock-123"
    public var inviterUserId = "inviter-mock-uid"

    public init() {}

    public func createInvite(uid: String, code: String, recoveryPhrase: String) async throws -> InvitePayload {
        lock.lock()
        defer { lock.unlock() }

        // Simulate server-side code collision if the same code is used twice.
        guard invites[code] == nil else {
            struct DuplicateCode: Error {}
            throw DuplicateCode()
        }

        let payload = InvitePayload(
            code: code,
            wrappedCoupleKey: "wrapped-mock-\(code)",
            kdfSalt: "salt-mock-\(code)",
            kdfParams: CoupleEncryptionManager.kdfParamsTag,
            encryptedRecoveryPhrase: "phrase-mock-\(code)"
        )
        invites[code] = payload
        return payload
    }

    public func acceptInvite(code: String, inviterUserId: String, recoveryPhrase: String) async throws -> AcceptResult {
        lock.lock()
        defer { lock.unlock() }

        lastAcceptedCode = code
        guard let payload = invites[code] else {
            struct NotFound: Error {}
            throw NotFound()
        }
        return AcceptResult(
            coupleId: nextCoupleId,
            inviterUserId: self.inviterUserId,
            wrappedCoupleKey: payload.wrappedCoupleKey,
            kdfSalt: payload.kdfSalt,
            kdfParams: payload.kdfParams,
            encryptedRecoveryPhrase: payload.encryptedRecoveryPhrase
        )
    }
}